Data recording method and apparatus, data recording medium, and data reproducing method and apparatus

ABSTRACT

The present invention provides remarkably improved availability in a data recording method and apparatus, a data recording medium, and a data reproducing method and apparatus. By recording additional information for data reproduction in each sector on a data reproducing medium as a subcode separately from data when the data is recorded in the unit of sector, reproduction of data can be controlled using the subcode, thus making it possible to remarkably improve the availability of the data recording medium.

TECHNICAL FIELD

[0001] The present invention relates to a data recording method andapparatus, a data recording medium, and a data reproducing method andapparatus. The present invention may be applicable, for example, to amethod and an apparatus for recording and reproducing video data, audiodata, caption data, and data composed of a plurality of these data aswell as data produced on a computer in accordance with the stipulationof ISO11172 (MPEG1) or ISO13818 (MPEG2).

BACKGROUND ART

[0002] Heretofore, a data recording medium such as a compact disc (atrade mark) has additional information data (subcode) recorded thereonfor realizing random access, in addition to information to be primarilyreproduced. The information to be primarily reproduced is subjected to amechanism for correcting errors with information located before andbehind the errors. Specifically, CIRC (Cross Interleaved Reed-SolomonCode) or the like is added to the information for countermeasures tosuch errors.

[0003] Thus, data can be utilized only after the lapse of a timerequired to read data before and behind certain data for performing theerror correction processing and a time required to calculations for theerror correction. Essentially, unlike reproducible data, the additionalinformation data is required to be utilized in a shorter time after itis read from a data recording medium, so that the error correctionprocessing is not performed for the additional information data, ordifferent error correction processing with a different calculationmethod from that for data to be primarily reproduced is employed for theadditional information data.

[0004] As additional information data for randomly accessing a datarecording medium, the most necessary data is information indicative ofthe position of data on the data recording medium, i.e., the address.Since the compact disc or the like is a data recording medium which wasoriginally created for recording audio data and is characterized in thatinformation is recorded at a fixed bit rate, information (address) forspecifying each read-out unit (sector) on the data recording medium isrepresented by a numerical value based on the hour, minute, second andframe, i.e., information (time code) on reproduction passing time fromthe head of reproduced data.

[0005] Due to the characteristic of the compact disc that information isrecorded at a fixed bit rate, audio data reproduction passing timeinformation (time code) on the disc increases in proportion to anincrease in the distance (address) of data from the head positionthereof on the data recording medium, i.e., the disc. Consequently,designation of a particular read-out unit (sector) on the data recordingmedium may also be realized by specifying the reproduction passing timerepresented by hour, minute, second and frame.

[0006] However, since this address based on hour, minute, second andframe is denoted based on a 60-adic number or a 75-adic number utilizingthe number of frames per second, this address cannot be used as it isfor a data recording medium used by a computer system which basicallyspecifies addresses with binary codes (which may be denoted inhexadecimal). Thus, the MD (Mini-Disc (a trade mark)) standard and so onemploy a binary form as the address for specifying a sector. In thiscase, although a search cannot be made directly with reproductionpassing time information (time code), since information is recorded at afixed bit rate on the mini-disc and so on, conversion from a binary-formsector address to the reproduction passing time information (time code)can be realized by a proportional calculation.

[0007] However, if the bit rate of information varies, thecorrespondence between the conventional reproduction passing timeinformation represented by hour, minute, second and the number of framesand a sector address cannot be calculated. With a varying bit rate, evenif the time code was used as a second address, the rate of increase inthe reproduction passing time information (time code) would be differentbetween a higher bit rate portion and a lower bit rate portion, wherebytwo or more sectors would exist having the same passing time information(time code), or two adjacent sectors would not always have sequentialpassing time information (time code), causing a problem that the timecode is not appropriate as the sector address for specifying a positionof data on the data recording medium.

[0008] Also, as video data recorded on a data recording medium, videodata in conformity to the stipulation of ISO11172-2 (MPEG1 Video) orISO1818-2 (MPEG2 Video) may be occasionally recorded. This video datasuffers from technical restrictions on decoding. Specifically, thedecoding cannot be performed from an arbitrary position of a bit stream,but must be always started from an I-picture. In a current video CD orthe like, when a search is made on a data recording medium for startingto read data from an arbitrary position, the data read is not alwaysstarted from head of an the I-picture, so that data cannot be utilizeduntil the next I-picture is reached, causing a problem that the decodingcannot be started for this period.

[0009] For reproducing the video data, one may wish to selectivelydecode only I- and P-picture with a B-picture skipped, or one may wishto selectively decode only I-picture with B- and P-picture skipped. Theconventional video CD's and so on, nevertheless, have a problem thatthey do not contain thereon information indicating at which position ofa data recording medium picture data is accommodated and which of I-,P-, and B-picture data is accommodated, or information indicating thehead position of such picture data, so that a picture of an arbitrarypicture type cannot be selectively reproduced by a search operation.

[0010] Furthermore, since respective picture data of the video data,after encoded, are recorded in an order different from the order inwhich they are displayed, a temporal reference is described in a pictureheader of the video data for indicating the display order. However, nospecific method has been thought for allowing the user to make a searchby specifying a number of the temporal reference.

[0011] Also, the current data recording medium such as the compact dischas only one bit of management information on copyright, i.e., how todeal with duplication. More specifically, only one bit is assigned toinformation indicating whether duplication of data recorded on the datarecording medium is prohibited or permitted. This limits to only twokinds of determinations, that is, duplication is prohibited orpermitted. Thus, such insufficient management information implies aproblem that it is impossible to achieve detailed copyright managementin combination of a plurality of conditions including whether or notduplication is permitted in a converted analog data form; whether or notduplication is permitted in a digital data form; whether or not data maybe output to computer equipment; whether or not data may be output toaudio-visual equipment other than a computer; and so on, and thatrepetitive duplications cannot be restricted.

[0012] Also, in the current compact disc and so on, an additionalinformation data portion for use in accessing certain data is providedin a fixed configuration, thus presenting few freedom for using thecompact disc in a variety of ways, e.g., for using the compact disc soas to support a plurality of applications.

DISCLOSURE OF THE INVENTION

[0013] The present invention has been made in view of the foregoingaspects, and proposes a data recording method and apparatus, a datarecording medium, and a data reproducing method and apparatus which arecapable of solving the conventional problems at a stroke and remarkablyimproving the usability as a whole.

[0014] To solve the problems mentioned above, the present inventionprovides a data recording method for recording data in the unit ofsector on a data recording medium, wherein additional information fordata reproduction is recorded as a subcode in each sector separatelyfrom data.

[0015] The present invention also provides a data recording apparatusfor recording data in the unit of sector on a data recording mediumwhich comprises subcode generating means for generating a subcode asadditional information for data reproduction in each sector separatelyfrom data recorded therein; and subcode adding means for recording dataand the subcode in each sector. of sector, the subcode can be used tocontrol the data reproduction to remarkably improve the availability ofthe data recording medium.

[0016] Upon reproducing a data recording medium which has the subcodeserving as additional information for data reproduction recorded in eachsector separately from data when the data was recorded in the unit ofsector, the subcode recorded in each sector is reproduced independentlyof the reproduction of the data recorded in each sector to control thedata reproduction, thereby making it possible to support a variety ofreproducing methods and provide improved usability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a block diagram showing the configuration of anembodiment of a data recording apparatus according to the presentinvention.

[0018]FIG. 2 is a block diagram showing the configuration of anembodiment of a data reproducing apparatus according to the presentinvention.

[0019]FIG. 3 is a table explaining a sector structure as an embodimentof a data recording format according to the present invention.

[0020]FIG. 4 i a schematic diagram explaining user data recorded in asector structure in accordance with the data recording format of FIG. 3.

[0021]FIG. 5 is a table explaining a synchronization pattern in thesector structure in accordance with the data recording format of FIG. 3.

[0022]FIG. 6 is a table showing a structure for adding a time code to asubcode in the sector structure in accordance with the data recordingformat of FIG. 3.

[0023]FIG. 7 is a table showing a structure for adding entry pointinformation to the subcode in the sector structure in accordance withthe data recording format of FIG. 3.

[0024]FIG. 8 is a table showing a structure for adding picture headerinformation to the subcode in the sector structure in accordance withthe data recording format of FIG. 3.

[0025]FIG. 9 is a table showing a structure for adding a temporalreference to the subcode in the sector structure in accordance with thedata recording format of FIG. 3.

[0026]FIG. 10 is a table showing a structure for adding copyrightmanagement information to the subcode in a sector structure inaccordance with the data recording format of FIG. 3.

[0027]FIG. 11 is a table showing the contents of a time code which isadded as the subcode of FIG. 6.

[0028]FIG. 12 is a table showing the contents of a time code which isadded as the subcode of FIG. 6.

[0029]FIG. 13 is a table showing the contents of a time code which isadded as the subcode of FIG. 6.

[0030]FIG. 14 is a table showing the contents of picture headerinformation which is added as the subcode of FIG. 6.

[0031]FIG. 15 is a table showing the contents of picture headerinformation which is added as the subcode of FIG. 6.

[0032]FIG. 16 is a table showing the contents of picture headerinformation which is added as the subcode of FIG. 6.

[0033]FIG. 17 is a table showing picture types as the picture headerinformation of FIGS. 15 and 16.

[0034]FIG. 18 is a table showing another structure of the subcode in thesector structure in accordance with the data recording format of FIG. 3.

[0035]FIG. 19 is a table showing the contents of copyright informationwhich is added as the subcode of FIG. 18.

[0036]FIG. 20 is a table showing the contents of a duplication codefield in FIG. 19.

[0037]FIG. 21 is a table showing the contents of a layer informationfield which is added as the subcode of FIG. 18.

[0038]FIG. 22 is a table showing the contents of a number of layersfield in the layer information of FIG. 21.

[0039]FIG. 23 is a table showing the contents of a layer number field inthe layer information of FIG. 21.

[0040]FIG. 24 is a table showing the contents of an applicationidentification number field which are added as the subcode of FIG. 18.

BEST MODE FOR EMBODYING THE PRESENT INVENTION

[0041] One embodiment of the present invention will be described indetail with reference to the accompanying drawings.

[0042] (1) Data Recording Format

[0043] (1-1) Sector Structure

[0044] A data recording medium according to this embodiment is a mediumwhich is capable of recording and storing data thereon, for example, acompact disc, a magneto-optical disc, a hard disc, and so on, where userdata including video data, audio data, caption data, data composed of aplurality of these data, and data produced on a computer as well asadditional information including a subcode and so on are recorded by adata recording apparatus in a sector structure defined in accordancewith a data recording format shown in FIG. 3 at a variable data rate.

[0045] In third data recording format, the size of a user data field ina sector is selected to be 2,048 bytes. Also in this embodiment, onepacket is defined so as not to extend over a plurality of sectors ofuser data, so that the length of one packet should be 2,048 bytes atmaximum or less. The user data in each sector always has a packet headeradded at the head thereof, as shown in FIGS. 4(A)-4(C).

[0046] Actually, placed at the head of each sector is a four-bitsynchronization pattern comprising one of fixed patterns as shown inFIG. 5 by which the head of each sector is detected. Subsequent to thissynchronization pattern, a two-byte CRC (Cyclic Redundancy Check) codeis calculated and added for a subcode which is placed behind the CRCcode. The subcode added subsequent to the CRC code includes a variety ofidentification information on user data. The subcode has a 14-bytelength. Subsequent to the subcode, the above-mentioned user data isadded, followed by a four-byte CRC code calculated from and added forthe subcode, the CRC code for the subcode and the user data. For thesake of convenience, the four-byte CRC code calculated from the subcode,CRC code and user data is called the “EDC”. For these synchronizationpattern, subcode, CRC code, user data, and EDC, two kinds of parities C1and C2 having different interleave directions created in accordance withthe cross interleaved Reed-Solomon code, i.e. 308 bytes of ECC (ErrorCorrection Code) is added to complete a sector consisting of 2,380 bytesof recording data which is recorded on a data recording medium forstorage and reproduction.

[0047] (1-2) Structure of Subcode

[0048] In the above described data recording format, four-byte time codeinformation (FIG. 6), one-byte entry point information (FIG. 7),one-byte picture header information (FIG. 8), two-byte temporalreference information (FIG. 9), or four-byte copyright managementinformation (FIG. 10) is used in addition to a four-byte sector number(a sector address) as the contents of the subcode, as shown in FIGS.6-10.

[0049] Actually, with the sector number and the time code informationbeing used for the subcode as shown in FIG. 6, the position of eachsector can be specified even if data is recorded on a data recordingmedium at a variable data rate, the sector address can be specified in amanner suitable for a data recording medium used in a computer system,and a search using the time code information can be easily realized forreproduction, thus making it possible to extent applicable areas of thedata recording medium.

[0050] A data format for the time code information may be implemented bya time code having fields of hour, minute, second, {fraction (1/10)}second, and {fraction (1/100)} second, as shown in FIG. 11. This is adata format commonly usable as the time code for video data, audio dataand caption data. Time code information exclusive to video data may beimplemented by a time code having fields of hour, minute, second, and anumber of frames of a video signal, as shown in FIG. 12. In the case ofFIGS. 11 and 12, all fields are described in a BCD (Binary CodedDecimal) notation.

[0051] A further data format for the time code information may employ atime code format stipulated in ISO13818-2 (MPEG2 Video) as shown in FIG.13. Since this format permits a time code included in video data and atime code included in additional information to be analyzed by the samemethod, an analysis circuit or an analysis program can be shared by thevideo data and the additional information. Also, since respective fieldsof this format are described in a binary notation, the time codeinformation can be written with a less amount of information thanwriting a time code described in a BCD notation into additionalinformation. Thus, if a fixed length subcode is employed, further,information may be added thereto by the reduced amount.

[0052] The entry point information, stored in the subcode shown in FIG.7, is flag information which is set only for a sector including the headposition of a I-picture. Specifically explaining, this flag information,set only for a sector including the head position of an I-picture isprovided such that when a data reproducing apparatus is adapted to startreading out data by detecting the flag information, the decoding can beinitiated immediately from the head of the I-picture. In this way,reproduction can be started immediately after a high-speed searchoperation.

[0053] The picture header information, stored in the subcode shown inFIG. 8, may comprise a one-bit picture header flag which is set only fora sector including the head position of a picture as shown in FIG. 14;two-bit picture type information (indicative of an I-, P-. or B-picture)as shown in FIG. 15; or both of the picture header flag and the picturetype information as shown in FIG. 16. As to the picture type, two-bitpatterns are assigned to the I-picture, P-picture, and B-picture,respectively, as shown in FIG. 17. It should be noted that the two-bitpattern indicative of an I-picture is added as a subcode when at leastI-picture data exist in a corresponding sector; the two-bit patternindicative of a P-picture is added when I-picture data does not existbut P-picture data exists in a corresponding sector; and the two-bitpattern indicative of a B-picture is added when neither I-picture datanor P-picture data exist but B-picture data only exists in acorresponding sector.

[0054] By thus adding the picture header information to the subcode suchthat a reproducing apparatus detects it to control a data readoperation, data can be initially read from the head position of apicture, or alternatively, selective reproduction based on the picturetype can be implemented in such a manner that a picture to be decoded isread while a picture not to be decoded is skipped.

[0055] The temporal reference information, stored in the subcode shownin FIG. 9, refers to a temporal reference existing in a picture layerwithin a bit stream stipulated by ISO11172-2 (MPEG1 Video) or ISO13818-2(MPEG2 Video) for indicating an order in which respective pictures areto be displayed. By thus providing the subcode with the temporalreference information such that a data reproducing apparatus startsreading data upon detecting the temporal reference information, the datareproducing apparatus can access to a picture with a temporal referencenumber specified by the user.

[0056] The copyright management information, stored in the subcode shownin FIG. 10, includes one-byte information indicating how to treat thecopyright for each of digital video, analog video, digital audio, andanalog audio data. The set of one-byte copyright information added as asubcode provides for copyright management in combination of a pluralityof conditions in accordance with data creator or recorder's intention.

[0057] The subcode may also take a form shown in FIG. 18. Asillustrated, when the subcode is formatted to include copyrightinformation, layer information, sector number (sector address), tracknumber, application identification number, and application information,this single structure subcode enables a data recording medium to supporta variety of applications.

[0058] The copyright information shown in FIG. 18 indicates attributeswith respect to duplication of user data included in an associatedsector with a two-bit duplication code as shown in FIG. 19. Theduplication code has two-bit patterns as shown in FIG. 20 which areassigned to attributes of “Duplication Permitted”, “Duplication OncePermitted”, and “Duplication Prohibited”, respectively.

[0059] The layer information is used when a disc comprises a pluralityof layers to indicate how many layers the disc including a sector isformed of, and which of the layers the sector is contained.

[0060] More specifically, the layer information in FIG. 18 representsinformation on a disc and a layer including a sector with three-bitfields denoted “Number of Layers” and “Layer Number” as shown in FIG.21. “Number of Layers” is set to “1” when a disc including the sector isformed of a single layer, and to “2” when the disc is formed of twolayers. Numerical values other than “1” and “2” are reserved.

[0061] “Layer Number”, as shown in FIG. 23, is set to “0” when a layerincluding a sector is a first layer, and to “1” when it is a secondlayer. Numerical values other than “0” and “1” are reserved.

[0062] The track number shown in FIG. 18 is provided for realizing amechanism of a track utilized for searching for the head of a musictitle on a compact disc or the like. The track is defined as a set ofsequential sectors on a disc and denoted a track number.

[0063] The application identification number shown in FIG. 18 isprovided for classifying the contents of information written in a userdata portion of FIG. 3 in accordance with applications associated withthe information. For example, supposing that a portion of a disccontains data for a so-called application DVD (Digital Video Disc), andthe other portion contains data for another application (for example, anaudio application), a different number is recorded in the applicationidentification number field of the subcode associated with each data toallow easy discrimination of data for different applications uponreproduction. The application identification number is also used fordefining the kind of information recorded in the application informationfield subsequent to the application identification number field.

[0064]FIG. 24 shows, by way of example, the definition of applicationidentification number. When the application identification number is setto “0”, the subsequent application information field is filled with “0”.

[0065] Also, when the application identification number is set to “1”,DVD (Digital Video Disc) data is recorded in the user data area of anassociated sector, and information regarded to be important to DVD iswritten into the application information field. For example, theapplication information field may contain information on the entrypoint, described above with reference to FIG. 7 which is very importantinformation for the MPEG standard used in DVD.

[0066] When the application identification number is set to “2”, audiodata is recorded in the user data area of an associated sector, so thatinformation regarded to be important to audio is recorded in theapplication information field. For example, the sampling frequency, bitlength, and so on of audio data are recorded to help the operation of areproducing apparatus.

[0067] When the application identification number is set to “254”, theuser data area of an associated sector is filled with “0”. Theapplication identification number from “3” to “253” and “255” isreserved here.

[0068] According to the foregoing recording format, video data, audiodata, caption data, data composed of a plurality of these data, and dataproduced on a computer are recorded in the unit of sector, and time codeinformation, entry point information, picture header information,temporal reference information, or track number is added as a subcode toeach sector in addition to a sector number, thus making it possible torealize a data recording medium which can remarkably improve theusability thereof for special reproduction, search and reproduction, andso on performed on the reproducing apparatus side, even if data isrecorded thereon at a variable data rate.

[0069] Also, with the information on copyright added as a subcode toeach sector, it is possible to realize a data recording medium withwhich detailed copyright management can be achieved for each sector onthe reproducing apparatus side.

[0070] Further, with the layer information added as a subcode to eachsector, it is possible to realize a data recording medium from whichrecorded data extending over a plurality of layers can be reproduced bya reproducing apparatus.

[0071] Furthermore, by recording the application identification numberand the application information, information required by a variety ofapplications can be easily recorded in each subcode, thus making itpossible to realize a data recording medium which can remarkably improvethe usability.

[0072] (2) Data Recording Apparatus According to Embodiment

[0073] Referring to FIG. 1, reference numeral 1 generally designates adata recording apparatus which records data in the data recording formataccording to the present invention which has been described withreference to FIGS. 3-17 and 18-24. The data recording apparatus 1 ofthis embodiment multiplexes video data, audio data, caption data, aprogram composed of a plurality of these data, and data produced on acomputer, adds additional information such as the subcode to the data,and records them on a data recording medium 19.

[0074] In this data recording apparatus 1, a master data supply unit 2,in response to a command from a control unit 20, supplies previouslyproduced video data, audio data, and caption data to a video encoder 5,an audio encoder 8, and a caption encoder 7, respectively. This masterdata supply unit 2 comprises, for example, a video tape player forbusiness use. When time code information is found in a sector togetherwith video data, audio data and caption data, the master data supplyunit 2 supplies the time code information to a time code informationswitching circuit 10.

[0075] A computer 3, in response to a command from the control unit 20,supplies a computer interface 4 with computer data to be recorded on thedata recording medium 19. The computer interface 4 converts electriccharacteristics, signal format, data format, and so on of informationsent from the computer 3, and supplies a multiplexer circuit 8 with theinformation converted but having the same contents.

[0076] The video encoder 5 encodes video data sent from the master datasupply unit 2 in accordance with a coding procedure stipulated byISO11172-2 (MPEG1 Video) or ISO13818-2 (MPEG2 Video), and suppliesencoded video data to the multiplexer circuit 8. The video encoder 5also supplies a subcode encoder 11 with entry point informationindicative of a position at which I-picture data is found; pictureheader information indicative of a position at which a picture header isfound; picture type information indicative of the type of a picture; andtemporal reference indicative of an order in which respective picturesare displayed.

[0077] The audio encoder 6 supplies the multiplexer circuit 8 with audiodata sent fro the master data supply unit 2 as it is or after encodingit in accordance with a coding procedure stipulated in ATRAC (AdaptiveTransform Acoustic Coding) which complies with ISO11172-3 (MPEG1 Audio),ISO13818-3 (MPEG2 Audio) or MD (mini-disc) standard. The caption encoder7 supplies the multiplexer circuit 8 with caption data sent from themaster data supply unit 2 as it is or after subjecting it to run-lengthcompress.

[0078] The multiplexer circuit 8 multiplexes data sent from the videoencoder 5, audio encoder 6, caption encoder 7, and computer interface 4in conformity to the stipulation of ISO1172-1 (MPEG1 System) orISO13818-1 (MPEG2 System). In this event, the multiplexer circuit 8receives an indication from the control unit 20 as to a processing unitof data which can be read from or written into the data recording medium19 at a time, i.e., an amount of user data recorded in a sector,multiplexes data so as to prevent a packet from extending over user dataareas in a plurality of sectors, and supplies multiplexed user data to asubcode adding circuit 15. Simultaneously with this, the multiplexercircuit 8 also supplies a sector boundary signal indicative of aboundary between sectors to the subcode adding circuit 15.

[0079] A time code information generator 9 generates time codeinformation in response to a command from the control unit 20. The timecode information switching circuit 10 selects one from time codeinformation sent from the master data supply unit 2 and time codeinformation sent from the time code information generator 9, andsupplies selected one to the subcode encoder 11. Note that the time codeinformation switching circuit 10 selects time code information sent fromthe master data supply unit 2 whenever it is sent therefrom, and selectstime code information sent from the time code information generator 9when no time code information is sent from the master data supply unit2.

[0080] The subcode encoder 11 encodes sector number information sentfrom the control unit 20 and other additional information into apredetermined format, and supplies the encoded information to a CRCencoder 12. The other additional information mentioned above refers tocopyright management information, time code information sent from thetime code information switching circuit 10, and entry point information,picture header information, picture type information or temporalreference information sent from the video encoder 5.

[0081] Further additional information may include layer information,track number, application identification number, and applicationinformation inputted from an input unit not shown. If the applicationidentification number indicates, for example, DVD, the applicationinformation has the entry point information sent from the video encoder5.

[0082] The CRC encoder 12 calculates CRC for subcode information sentfrom the subcode encoder 11, adds the CRC data to the subcodeinformation, further calculates EDC, adds the EDC to the subcodeinformation, and supplies the subcode information with the additionalCRC and EDC to a synchronization pattern adding circuit 13. Thesynchronization pattern adding circuit 13, in turn, adds thesynchronization pattern shown in FIG. 5 to the supplied subcodeinformation and supplies them to a subcode buffer 14. The subcode addingcircuit 15 inserts the subcode information read from the subcode buffer14 at the boundary of each sector in data sent from the multiplexercircuit 8. The position at which the subcode information is inserted isdetermined on the basis of a sector boundary signal sent from themultiplexer circuit 8. An ECC encoder 16 uses multiplexed data sent fromthe subcode adding circuit 15 to calculate C1 and C2 parities, i.e., ECCin accordance with Reed-Solomon code, adds the ECC to the multiplexeddata, and supplies them to a modulator circuit 17.

[0083] The modulator circuit 17 is a circuit for modulating data sentfrom the ECC encoder 16 to a signal format recordable on the datarecording medium 19, and performs EFM (Eight to Fourteen Modulation), byway of example. A writer unit 18 electrically, magnetically, optically,and/or physically records signals sent from the modulator circuit 17 onthe data recording medium 19.

[0084] While in this embodiment, the ECC, i.e., the parities arecalculated for and added to the multiplexed data after the subcode isadded thereto, the data recording apparatus 1 may be constructed to addthe subcode to the multiplexed data sent from the multiplexer circuit 8after the ECC is added to the multiplexed data.

[0085] The control unit 20 supplies a supply command to the master datasupply unit 2 and the computer 3 in accordance with editing instructionsfrom the user, indicates the processing unit of read/write, i.e., thesize of a sector for the data recording medium 19 to the multiplexercircuit 8, and supplies a time code generating command to the time codeinformation generator 9. The control unit 20 also supplies a switchingcommand to the time code switching circuit 10, receives a commandrelated to copyright management, layer information, track number,application identification number, and application information from aninput unit, not shown, and supplies the subcode encoder 11 with sectornumber information, copyright management information, layer information,track number, application identification number, and applicationinformation.

[0086] In the foregoing configuration, the control unit 20 firstcommands the master data supply unit 2 or the computer 3 to supply datain accordance with editing instructions from the user, and indicates thesize of a sector to the multiplexer circuit 8. The control unit 20 alsogenerates sector number information, copyright management information,layer information, track number, application identification number, andapplication information for recording in the subcode which are suppliedto the subcode encoder 11. Further, if no time code information is sentfrom the master data supply unit 2, the control unit 20 commands thetime code information generator 9 to generate time code information inaccordance with instructions from the user.

[0087] The video encoder 5 encodes inputted video data in accordancewith ISO11172-2 (MPEG1 Video) or ISO13818-2 (MPEG2 Video), and suppliesthe encoded video data to the multiplexer circuit 8. In this event,picture type information indicative of the type of an encoded picture(I-picture, P-picture, or B-picture) and temporal reference informationare supplied to the subcode encoder 11. Also, when a picture header issent, information indicating that a picture header exists is alsosupplied to the subcode encoder 11. In particular, when an I-picture issent, information indicating that an I-picture header exists, i.e.,entry point information is supplied to the subcode encoder 11.

[0088] The audio encoder 6 and the caption encoder 7 respectively encodean audio signal and a caption signal inputted thereto, and supply theencoded signals to the multiplexer circuit 8. The multiplexer circuit 8multiplexes data sent from the video encoder 5, audio encoder 6, andcaption encoder 7 in conformity to the stipulation of ISO1172-1 (MPEG1System) or ISO13818-1 (MPEG2 System).

[0089] The user data divided into packets per sector by the multiplexercircuit 8 is supplied to the subcode adding circuit 15 and the CRCencoder 12. The multiplexer circuit 8 also supplies the subcode addingcircuit 15 with a sector boundary signal which is set to “1” only whenthe first byte of user data, i.e., data indicative of the boundary of asector is delivered and to “0” in other cases.

[0090] The subcode encoder 11 in turn creates subcode data in accordancewith the subcode structures shown in FIGS. 6-10 and 18-24. Morespecifically, the subcode encoder 11 composes a subcode of a sectornumber and a time code (FIG. 6); the sector number and entry pointinformation (FIG. 7); the sector number and picture header information(FIG. 8); the sector number and temporal reference (FIG. 9); the sectornumber and copyright management information (FIG. 10); or the copyrightmanagement information, layer information, sector number, track number,application identification number, and application information as shownin FIG. 18, all of which are extracted from the data sent thereto, andsupplies the composed subcode to the CRC encoder 12. The CRC encoder 12calculates CRC for the subcode data received from the subcode encoder11, and adds the CRC immediately before the subcode data. The CRCencoder 12 further calculates EDC from the user data sent from themultiplexer circuit 8 and the subcode data with the CRC added thereto,and supplies the synchronization pattern adding circuit 13 with this EDCtogether with the subcode data with the additional CRC data.

[0091] The synchronization pattern adding circuit 13 adds asynchronization pattern (FIG. 5) immediately before the subcode datawith the additional CRC data, and supplies the subcode data having theCRC data and the synchronization pattern to the subcode buffer 14. Thesubcode buffer 14 holes the sent data sequentially including thesynchronization pattern, CRC, and subcode data and EDC so as to supplythem to the subcode adding circuit 15 in response to a request from thesubcode adding circuit 15.

[0092] The subcode adding circuit 15 requests the subcode buffer 14 tosupply corresponding data sequentially including a synchronizationpattern, CRC, and subcode data based on a sector boundary signal sentfrom the multiplexer circuit 8, inserts the requested data immediatelybefore the user data sent from the multiplexer circuit 8, adds the EDCimmediately behind the user data, and supplies the ECC encoder 16 withthe user data having the subcode data and EDC added thereto.

[0093] The ECC encoder 16 calculates ECC for the multiplexed data sentfrom the subcode adding circuit 15, adds the calculated ECC to themultiplexed data, and supplies the multiplexed data with the ECC to themodulator circuit 17.

[0094] The modulator circuit 17 modulates the data sent from the ECCencoder 16, and supplies the modulated data to the writer unit 18 whichin turn records the sent data on the data recording medium 19.

[0095] According to the foregoing configuration, in parallel withprocessing for recording video data, audio data, caption data, datacomposed of a plurality of these data, and data produced on a computerin the unit of sector, a time code, entry point information, pictureheader information, temporal reference, copyright managementinformation, layer information, track number, application identificationnumber, or application information is generated as a subcode, and addedto an associated sector, thereby making it possible to realize a datarecording apparatus which can add useful subcode information on thereproduction side with a simple configuration.

[0096] (3) Data Reproducing Apparatus According to Embodiment

[0097] Referring now to FIG. 2, reference numeral 21 generallydesignates a data reproducing apparatus which reads video data, audiodata, caption data, data composed of a plurality of these data, and datareproduced on a computer together with additional information from thedata recording medium 19 on which such data is recorded in accordancewith the data recording format of the present invention described abovewith reference to FIGS. 3-17 and 18-24.

[0098] In this data reproducing apparatus 21, a drive unit 22 performsmechanical mounting and dismounting of a data recording medium 19, aswell as drives a pickup for reading signals from the data recordingmedium 19, which may be an optical head, a magnetic head, or amagneto-optical head, reads signals from the data recording medium 19 bymeans of the pickup, and supplies a demodulator circuit 23 withconsequently reproduced signals.

[0099] The demodulator circuit 23 demodulates signals sent from thedrive unit 22, and supplies the demodulated data to an ECC decoder 24. Ademodulating method employed herein corresponding to the modulatingmethod employed in the modulator circuit 16, and may be, for example,EFM demodulation.

[0100] The ECC decoder 24 performs calculations based on multiplexeddata and C1 of ECC or C1 and C2 of ECC sent from the demodulator circuit23 to detect whether errors are included in the multiplexed data andECC. In this event, correctable errors in the multiplexed data, ifdetected, are corrected, and the ECC is removed from the multiplexeddata. Then, the multiplexed data free from errors, which have beendetected and corrected, is supplied to a subcode extracting unit 26. Inthis event, the ECC decoder 24 adds an error flag, for example, to everyeight bits of the multiplexed data to be outputted. The error flag isset to “0” when associated eight bits of the multiplexed data include noerror or when errors have been completely corrected, and to “1” whenerrors were uncorrectable.

[0101] The subcode extracting unit 26 extracts subcode data and CRC fromevery one-sector portion of the multiplexed data sent from the ECCdecoder 24 based on a synchronization pattern thereof, supplies theextracted data and CRC to a CRC checker 35, and also supplies themultiplexed data including the subcode from the ECC decoder 24 to a ringbuffer 27.

[0102] The CRC checker 35 calculates CRC included in the subcode datasent from the subcode extracting unit 26 to detect whether errors areincluded in the subcode data. The subcode data is sent to a subcodebuffer 25 if no error is detected, whereas it is not sent to the subcodebuffer 25 if any error is detected. The subcode buffer 25 temporarilyholds the subcode data and supplies the held data to a control unit 33in response to a request therefrom.

[0103] The ring buffer 27 is a memory for eliminating rate fluctuationscaused by variable rate recording, which has a FIFO memory therein fortemporarily buffering the multiplexed data and the error flag sent fromthe subcode extractor 26 and for supplying the buffered data to ademultiplexer 28 in response to a request therefrom.

[0104] It should be noted that while subcode information is extractedimmediately after performing an error correction in the configuration ofthis embodiment, the subcode information may be extracted, for example,immediately before the error correction.

[0105] The demultiplexer 28 decomposes data sent from the ring buffer 27into a video stream, an audio bit stream, a caption bit stream, subcodedata and other bit streams in accordance with the stipulation ofISO11172-1 (MPEG1 System) or ISO13818-1 (MPEG2 System). Within thesedecomposed bit streams, the video bit stream is supplied to a videodecoder 29; the audio bit stream to an audio decoder 30; the caption bitstream to a caption decoder 31; the subcode data to the control unit 33;and the other bit streams, which may be regarded as computer data, to acomputer interface 34.

[0106] The video decoder 29 decodes the video bit stream sent from thedemultiplexer 28 in conformity to ISO11172-2 (MPEG1 Video) or ISO13818-2(MPEG2 Video) and supplies the decoded digital video signal to a hostprocessor 32.

[0107] The audio decoder 30 decodes the audio bit stream sent from thedemultiplexer 28 in conformity to ISO11172-3 (MPEG1 Audio) or ISO13818-3(MPEG2 Audio) and outputs the decoded digital audio signal to a digitalaudio output terminal and to a D/A convertor 37. Alternatively, theoutputting of the digital audio signal to the digital audio outputterminal may be prohibited by a command from the control unit 33.

[0108] The caption decoder 31 expands the caption bit stream sent fromthe demultiplexer 28, if it has undergone run-length compress, and thensupplies the expanded caption data to the host processor 32. The hostprocessor 32 in turn superimposes the caption data sent from the captiondecoder 31 on the video data sent from the video decoder 29, and outputsthe superimposed digital video signal to a digital video outputterminal, and to a D/A and NTSC converter 36. Alternatively, theoutputting of the digital video signal to the digital video signaloutput terminal may be prohibited by a command from the control unit 33.

[0109] The control unit 33 controls the ECC decoder 24, thedemultiplexer 28, the video decoder 29, the caption decoder 31, the hostprocessor 32, and so on based on a variety of instructions inputted fromthe user through an input unit, not shown. The control unit 33 alsosends a command to the drive unit 22 to start reading the data recordingmedium 19, issues a seek command to the drive unit 22 to seek certaindata, issues a normal reproduction recover command to the drive unit 22to resume normal reproduction from a seek operation, read subcode datafrom the subcode buffer 25, and issues the seek command and the normalreproduction recover command based on the subcode data. Incidentally, inthis embodiment, the control unit 33 fetches a subcode also from thedemultiplexer 28. This is because temporary storage of data in the ringbuffer 27 causes a delay in data outputted from the ring buffer 27, sothat a subcode extracted by the subcode extracting unit 26 presents atime difference from a subcode for a sector corresponding to currentvideo bit stream, audio bit stream, caption bit stream and other bitstream which are being decomposed by the demultiplexer 28. For thisreason, the control unit 33 fetches a subcode also from thedemultiplexer 28 during normal reproduction in order to obtain a timecode, a sector number and so on in a subcode for a sector correspondingto data which is currently being decomposed and is actually ready fordecoding.

[0110] The computer interface 34 temporarily holds bit streams sent fromthe demultiplexer 28, converts electric characteristics, signal formatand data format of the bit streams so as to permit a computer to receivethem, and outputs the converted data to a computer data output.

[0111] The D/A and NTSC convertor 36 converts a digital video signalsent from the host processor 32 to an analog video signal, encodes theanalog video signal to an NTSC signal, and outputs the NTSC encodedsignal to an analog video output terminal. Alternatively, the convertor36 may be prohibited from outputting the video signal to the analogvideo output terminal by a command from the control unit 33. The D/Aconvertor 37 converts a digital audio signal sent from the audio decoder30 to an analog audio signal, and outputs the analog audio signal to ananalog audio output terminal. Alternatively, the D/A convertor 37 may beprohibited from outputting the analog audio signal to the analog audiooutput terminal by a command from the control unit 33.

[0112] Although not shown, an EDC checker may be provided at the rearstage of the ECC decoder to detect errors in user data using EDC inmultiplexed data.

[0113] In the foregoing configuration, the control unit 33 firstreceives reproduction instructions from the user, and issues a seekcommand to the drive unit 22. The drive unit 22 moves the pickup to apredetermined position to read a signal from the data recording medium19, and supplies the read signal to the demodulator unit 23. The signalfrom the drive unit 22 is demodulated by the demodulator 23 and suppliedto the ECC decoder 24. The ECC decoder 24 performs error detection andcorrection using ECC consisting of C1 and C2 parities sent theretotogether with multiplexed data to correct correctable errors, andsupplies the multiplexed data free from errors to the subcode extractingunit 26. The subcode extracting unit 26 detects a synchronizationpattern from the supplied multiplexed data, and supplies a subcode andCRC to the CRC checker 35 and the multiplexed data to the ring buffer27, respectively, based on the position of the detected synchronizationpattern.

[0114] The user data or multiplexed data sent to the ring buffer 27 issupplied to the demultiplexer 28, and therein decomposed into a videobit stream, an audio bit stream, a caption bit stream, subcode data, andother bit stream, each of which is supplied to the video decoder 29, theaudio decoder 30, the caption decoder 31, the control unit 33, and thecomputer interface 34, respectively.

[0115] The video bit stream sent to the video decoder 29 is decodedtherein and supplied to the host processor 32. The audio bit stream sentto the audio decoder 30 is decoded therein and outputted to the digitalaudio output terminal and to the D/A convertor 37. The digital audiosignal sent to the D/A convertor 37 is converted into an analog audiosignal and outputted to the analog audio output terminal.

[0116] The caption bit stream sent to the caption decoder 31 isexpanded, if it has undergone run-length compress, and supplied to thehost processor 32. The host processor 32 superimposes the caption datasent from the caption decoder 31 on the video data sent from the videodecoder 29, and outputs the superimposed video data to the digital videooutput terminal and to the D/A and NTSC convertor 36.

[0117] When subcode data is held in the subcode buffer 25, the controlunit 33 read out the subcode data to empty the subcode buffer 25. When asubcode read from the subcode buffer 25 or the demultiplexer 28 is inthe form shown in FIG. 10, the control unit 33 refers to copyrightmanagement information included in the subcode data to issue an outputenable command or an output disable command for the respective digitaland analog output terminals for video and audio signals. When acorresponding byte of the copyright management information is other than“0”, the control unit 33 commands the host processor 32, the D/A andNTSC convertor 36, the audio decoder 30, and the D/A convertor 37 todisable outputting the video and audio signals.

[0118] When the read subcode data is in the form shown in FIG. 6, it isassumed that a search is made based on a time code specified by the userduring normal reproduction. The control unit 33 stores a time code ofcurrently reproduced data from subcode data thereof during normalreproduction. When a new search is instructed by the user, the storedtime code is compared with a time code specified by the user. Then, thecontrol unit 33 commands the drive unit 22 to move the pickup toward thedirection in which data corresponding to the specified time code exists,i.e., from a current sector in the direction of increasing or decreasingthe sector number of the current sector, for reading the data.

[0119] A subcode of the data read from a sector to which the pickup hasbeen moved is sent through the demodulator circuit 23, the ECC decoder24, the subcode extracting unit 26, the CRC checker 35, and the subcodebuffer 25 to the control unit 33 which reads, from the subcode, a timecode in the subcode corresponding to the sector. If the time code of thesector to which the pickup has been moved is not coincident to orsufficiently close to the time code specified by the user, the controlunit 33 again commands the drive unit 22 to move the pickup to repeatthe above-mentioned operations. when the time code of a sector to whichthe pickup has been moved is coincident to or sufficiently close to thetime code specified by the user, the search operation is stopped toresume normal reproduction from the position at which the pickup iscurrently placed. In this way, since the search operation is performedusing the time code added as a subcode, the data reproducing apparatus21 provides high-speed random access.

[0120] When the read subcode data is in the form shown in FIG. 7, asearch is made based on an entry point when instructed by the userduring normal reproduction. The control unit 33, responsive toinstructions from the user, commands the drive unit 22 to move thepickup from a current sector in the direction of increasing ordecreasing the sector number of the current sector by a predeterminedamount to read multiplexed data from the data recording medium 19.

[0121] A subcode of the data read from a sector to which the pickup hasbeen moved is sent through the demodulator circuit 23, the ECC decoder24, the subcode extractor 26, the CRC checker 35, and the subcode buffer25 to the control unit 33 which reads entry point information in thesubcode corresponding to the sector. If an entry point flag is not setfor the sector to which the pickup has been moved, the control unit 33again commands the drive unit 22 to move the pickup to repeat theabove-mentioned operations. If the entry point flag is set for thesector to which the pickup has been moved, the search operation isstopped to resume normal reproduction from the position at which thepickup is currently placed. In this event, since the entry point flagindicates the head position of an I-picture as described above, decodingcan be started immediately after the search operation. Also, during thesearch operation, the entry point in a subcode extracted by the subcodeextracting unit 26 is used without demultiplexing and decoding themultiplexed data, so that high speed random access can be achieved.

[0122] When the read subcode data is in the form of FIG. 8 with pictureheader information described as shown in FIG. 14, a search is made basedon a picture header flag, when instructed by the user during normalreproduction. The control unit 33, responsive to instructions from theuser, commands the drive unit 22 to move the pickup from a currentsector in the direction of increasing or decreasing the sector number ofthe current sector by a predetermined amount to read multiplexed datafrom the data recording medium 19.

[0123] A subcode of the data read from a sector to which the pickup hasbeen moved is sent through the demodulator circuit 23, the ECC decoder24, the subcode extracting unit 26, the CRC checker 35, and the subcodebuffer 25 to the control unit 33 which reads the picture header flag inthe subcode. If the picture header flag is not set for the sector towhich the pickup has been moved, the control unit 33 again commands thedrive unit 22 to move the pick up to repeat the above-mentionedoperations. Conversely, if the picture header flag is set for the sectorto which the pickup has been moved, the control unit 33 stops the searchoperation to resume normal reproduction from the position at which thepickup is currently placed. In this way, a sector including the headposition of a picture can be promptly accessed without demultiplexingand decoding the multiplexed data.

[0124] If the read subcode data is in the form of FIG. 8 with thepicture information described as shown in FIG. 15, a search operationcan be performed such that only I-picture is selectively read anddecoded. With this subcode structure, a search, when instructed from theuser during normal operation, is made based on the picture type in thesubcode. The control unit 33, responsive to instructions from the user,commands the drive unit 22 to move the pickup from a current sector inthe direction of increasing or decreasing the sector number of thecurrent sector to read data from the data recording medium 19.

[0125] A subcode of the data read from a sector to which the pickup hasbeen moved is sent through the demodulator 23, the ECC decoder 24, thesubcode extracting unit 26, the CRC checker 35, and the subcode buffer25 to the control unit 33 which reads the picture type in the subcode.If the picture type of a sector to which the pickup has been moved doesnot indicate an I-picture, the control unit 33 again commands the driveunit 22 to move the pickup. If the pickup type of a sector to which thepickup was newly moved indicates I-picture, video data in this sector issupplied to the video decoder 29. Thereafter, the control unit 33repeatedly commands the drive unit 22 to move the pickup. In this way, asector including I-picture data can be accessed promptly withoutdemultiplexing and decoding multiplexed data. When the I-picture datathus obtained is decoded, exclusive reproduction of I-picture can beselectively realized.

[0126] With a similar procedure, I-picture and P-picture only can beselectively reproduced by skipping sectors, the subcode of which has thepicture type indicating a B-picture.

[0127] Incidentally, when the subcode data is in the form of FIG. 8 withthe picture header information described as shown in FIG. 14, a sectorincluding the head of a picture header is not always a sector includinga picture header of an I-picture. The video decoder 29 thereforerequires an operation for deleting read data until a sector including anI-picture is detected. Thus, although the search operation can be madefaster to some degree, it is impossible to immediately start decoding.Also, when the subcode data is in the form of FIG. 8 with the pictureheader information described as shown in FIG. 15, the first derivedI-picture data may not include a picture header, so that part of datamust be deleted in the video decoder 29.

[0128] In consideration of the foregoing, if the subcode data is in theform shown in FIG. 8 with the picture header information described asshown in FIG. 16, a sector including a picture header of an I-picturecan be specified, so that a search operation can be realized by fasterselective reproduction of picture. Further, with the subcode data in theformat of FIG. 9, when the user specifies a temporal reference number, asearch is made based on temporal reference n the subcode. The controlunit 33, responsive to instructions from the user, commands the driveunit 22 to move the pickup from a current sector in the direction ofincreasing or decreasing the sector number of the current sector by apredetermined amount to read multiplexed data from the data recordingmedium 19.

[0129] A subcode of the data read from a sector to which the pickup hasbeen moved is sent through the demodulator 23, the ECC decoder 24, thesubcode extracting unit 26, the CRC checker 35, and the subcode buffer25 to the control unit 33 which reads the temporal reference in thesubcode. The control unit 33 commands the drive unit 22 to move thepickup to repeat the above-mentioned operations until the temporalreference for the sector to which the pickup has been moved iscoincident with the temporal reference number specified by the user. Inthis way, data indicated by the temporal reference number specified bythe user can be promptly accessed without demultiplexing and decodingthe multiplexed data.

[0130] Likewise, when the subcode data is in the form shown in FIG. 18,random access to a particular track number, access to a sector having aparticular application identification number, and random access usingapplication information (entry point information is written herein), forexample, when the application identification number indicates DVD, canbe promptly performed respectively without demultiplexing and decodingdata.

[0131] More specifically, when the user instructs the control unit 33 toaccess a particular track number during normal reproduction, the controlunit 33 stores a track number of currently reproduced data, derived fromsubcode data of the currently reproduced data, during normalreproduction, compares this track number with the track number specifiedby the user for a new search, and commands the drive unit 22 to move thepickup toward the direction in which data having the specified tracknumber exists from a current sector in the direction of increasing ordecreasing the sector number of the current sector to read datatherefrom.

[0132] A subcode of the data read from a sector to which the pickup hasbeen moved is sent through the demodulator 23, the ECC decoder 24, thesubcode extracting unit 26, the CRC checker 35, and the subcode buffer25 to the control unit 33 which reads a track number in the subcodecorresponding to the sector. If the track number read from the sector towhich the pickup has been moved is not coincident with the track numberspecified by the user, the control unit 33 again commands the drive unit22 to move the pickup to repeat the above-mentioned operations. If thetrack number read from the sector to which the pickup has been moved iscoincident with the track number specified by the user, the control unit33 stops the search operation to resume normal reproduction from theposition at which the pickup is currently placed. In this way, sincedata is accessed using a track number added as the subcode withoutdemultiplexing and decoding the multiplexed data, fast, random accesscan be achieved. Likewise, using the application information in whichentry point information is described, fast random access can beperformed similarly to the case of the aforementioned FIG. 7.

[0133] Also, when the subcode data is in the form shown in FIG. 18, thecontrol unit 33 can determined whether a sector including dataassociated with a target application has been read by fetching anapplication identification number.

[0134] Further, when the subcode data is in the form shown in FIG. 18,assume that a two-layer disc is reproduced. A subcode of data read frothe disc is supplied to the controller 33 through the demodulator unit23, the ECC decoder 24, the subcode extracting unit 26, the CRC checker35, and the subcode buffer 24, or through the demodulator unit 23, theECC decoder 24, the subcode extracting unit 26, the ring buffer 27, andthe demultiplexer 28. The control unit 33 fetches a number of layers anda layer number of a currently read sector. If the layer number of thecurrently read sector is different from a target layer number, thecontrol unit 33 commands the drive unit 22 to switch the currently readlayer to the other layer. A read signal from the switched layer issupplied to the control unit 33 through a similar path. Then, if thelayer number of a sector from which the signal is being read is equal tothe target layer number, reproduction is continued.

[0135] Further, when the subcode data is in the form of FIG. 18, thecontrol unit 33 reads copyright management information in the subcode,and controls the outputs of the host processor 32, the D/A and NTSCconvertor 36, and the D/A convertor 37 in accordance with the contentsof the copyright management information. If the subcode indicates thatduplication is permitted only once, this information is delivered toexternally connected equipment.

[0136] When the above-mentioned search operations and random access areperformed, the control unit 33 commands the ECC decoder 24 to change anerror correction mode. This causes the ECC decoder 24 to perform theerror correction only with the C1 parity in multiplexed data. In thisway, the subcode data can be fetched more promptly. Of course, if theerror correction was performed with both C1 and C2 parities as is thecase of normal reproduction, the error correction capability would beenhanced. However, the error correction with the C1 and C2 paritieswould result in delaying in extracting the subcode data.

[0137] According to the foregoing configuration, when a data recordingmedium 19 on which video data, audio data, caption data, data composedof a plurality of these data, and data produced on a computer arerecorded in the unit of sector together with a time code, entry pointinformation, picture header information, temporal reference, or tracknumber as a subcode added to each sector, is reproduced at a variabledata rate, by separately reproducing the subcode alone, it is possibleto realize a data reproducing apparatus which provides remarkableimprovements in the usability for special reproduction, search andreproduction, and so on.

[0138] Also, since information on copyright is additionally recorded asa subcode for each sector on the data recording medium 19 and thissubcode is extracted when reproducing the data recording medium 19 foruse in copyright management, detailed copyright management can berealized for each sector.

[0139] Further, since layer information is additionally recorded as asubcode for each sector on the data recording medium 19 and this subcodeis extracted when reproducing the data recording medium, it is possibleto realize a data reproducing apparatus which can reproduce recordeddata extending over a plurality of layers with a simple configuration.

[0140] Further, since an application identification number andapplication information area recorded in each sector as a subcode on thedata recording medium and this subcode is extracted when reproducing thedata recording medium for controlling reproduction, it is possible torealize a data reproducing apparatus which provides remarkableimprovements in the usability.

[0141] (4) Other Embodiments

[0142] While in the foregoing embodiment, a subcode extracted by thesubcode extracting unit 26 is used when performing a search operation orrandom access, a subcode separated by the demultiplexer 28 may also beused for the purpose. It should be noted however that since the ringbuffer 27 causes a delay as described above, an improvement in operatingspeed will be limited as compared with the foregoing embodiment.

[0143] While the foregoing embodiment has been described for the casewhere a subcode is recorded in each sector prior to user data, thearrangement of the subcode is not limited to this. The subcode may becontained in 2,048 bytes of user data as other raw data different fromthe user data, or may be contained as data having a particular packetheader. Further alternatively, the subcode may be located in a datamanagement area which is reserved separately from a data recording area,i.e., a so-called TOC (Table of Contents) area in a compact disc or thelike.

[0144] While in the foregoing embodiment, the subcode has a length of 14bytes and the user data has a length of 2,048 bytes, the lengths of thesubcode and the user data are not limited to these values and may bearbitrary selected as required. Also, the length of the error correctioncode calculated for the subcode and the user data may be arbitrarilyselected in accordance with requirements to the error correction anddetection capability and so on.

[0145] The foregoing embodiment has been described for the case whereECC consisting of Reed-Solomon codes is added to the user data as anerror correction code while CRC and EDC are added to the subcode as anerror detection code. However, the kinds of error correction anddetection codes are not limited to the above. The point is that if theerror correction and detection codes are selected such that the subcodeis reproduced easier than the user data in view of a calculation timeand so on upon reproduction, similar effects to those of the foregoingembodiment can be realized.

[0146] While the foregoing embodiment has been described for the casewhere time code information, entry point information, picture headerinformation, temporal reference information, copyright managementinformation, layer information, track number or applicationidentification number is added as a subcode, similar effect as those ofthe foregoing embodiment can be realized also by combining them or byadding other additional information for data reproduction as a subcode,as required.

[0147] In the foregoing embodiment, one packet of video data, audiodata, caption data, data composed of a plurality of these data, and dataproduced on a computer is created so as not to extend over a pluralityof sectors. Alternatively, a region in which one or a plurality ofaudio/video tracks are recorded as user data may be regarded as one filein a file system such that a computer can manage and modify anassignment situation of a region for computer data and programs and aregion for recording audio/video data on a data recording medium.Further, in this case, the TOC area may be treated as a virtualdirectory in the file system, and audio/video data may be treated asfiles existing in the directory such that the audio/video data can beread from and written into a computer system.

[0148] While the foregoing embodiment has been described for the casewhere the present invention is applied to recording and reproducing ofvideo data, audio data, caption data, data composed of a plurality ofthese data, and data produced on a computer based on the stipulation ofISO11172 (MPEG1) or ISO13818 (MPEG2), the present invention is notlimited to this but is suitable for wide applications to data recordingmethods and apparatus, data recording media, and data reproducingmethods and apparatus which treat a variety of data.

[0149] While in the foregoing embodiment, the multiplexed data isassumed to be variable rate data, of course, it may be fixed rate data.

[0150] While the foregoing embodiment has been described on theassumption that the data recording medium 19 formed by the datarecording apparatus 1 is directly utilized as the data recording medium19 to be reproduced by the data reproducing apparatus 21, a recordingmedium reproduced by the data reproducing apparatus 21 may be one ofrecording media mass-produced by a stamper or the like from the datarecording medium 19 formed by the data recording apparatus 1 used as amaster recording medium.

[0151] According to the present invention as described above, by virtueof additional information for data reproduction serving as a subcodeseparately from data in each sector, which is added when the data isrecorded on a data recording medium in the unit of sector, it ispossible to realize a data recording method and apparatus as well as adata recording medium which can control data reproduction using thesubcode and hence can remarkably improve the usability of the datarecording medium.

[0152] Also, according to the present invention as described above, uponreproducing a data recording medium which has a subcode serving asadditional information for data reproduction in each sector separatelyfrom data, which was added when the data was recorded in the unit ofsector, the subcode recorded in each sector is reproduced separatelyfrom reproduction of data recorded in each sector, in order to controlthe reproduction of the data, thereby making it possible to realize adata reproducing method and apparatus which can support a variety ofreproducing methods and improve the usability.

Industrial Availability

[0153] The data recording method and apparatus of the present inventionmay be utilized to record compressed digital images, compressed digitalspeech and so on in a multiplex manner to create DVD (Digital VideoDisc). The data recording medium of the present invention, in turn, maybe utilized as DVD on which compressed digital images, compresseddigital speech and so on are recorded in a multiplex manner. Further,the data reproducing method and apparatus of the present invention maybe utilized to reproduce data from DVD on which compressed digitalimages, compressed digital speech and so on are recorded in a multiplexmanner.

1. A data recording method for recording data on a data recording mediumin the unit of sector, wherein: additional information for datareproduction is recorded in each of said sectors as a subcode separatelyfrom said data.
 2. The data recording method according to claim 1 ,wherein: video data, audio data, caption data, multiplexed dataincluding said video data and/or said audio data and/or said captiondata, or computer data is recorded as said data.
 3. The data recordingmethod according to claim 1 , wherein a sector number for identifyingsaid sector is added as said subcode.
 4. The data recording methodaccording to claim 3 , wherein a predetermined time code is added assaid subcode.
 5. The data recording method according to claim 3 ,wherein entry point information representing a sector including the headposition of an I-picture is added as said subcode, when video data inaccordance with the stipulation of ISO11172 (MPEG1) or ISO13818 (MPEG2)is recorded as said data.
 6. The data recording method according toclaim 3 , wherein picture type information representing the type of apicture included in data within an associated sector is added as saidsubcode, when video data in accordance with the stipulation of ISO11172(MPEG1) or ISO13818 (MPEG2) is recorded as said data.
 7. The datarecording method according to claim 3 , wherein temporal referenceinformation is added as said subcode, when video data in accordance withthe stipulation of ISO11172 (MPEG1) or ISO13818 (MPEG2) is recorded assaid data.
 8. The data recording method according to claim 3 , whereincopyright information for video data, audio data, caption data, orcomputer data is added as said subcode.
 9. The data recording methodaccording to claim 3 , wherein an application identification codecorresponding to an application associated with data in a sector, andinformation on each application are added as said subcode.
 10. The datarecording method according to claim 3 , wherein track information isadded as said subcode.
 11. A data recording apparatus for recording dataon a data recording medium in the unit of sector, comprising: generatingmeans for generating user data; subcode generating means for generatinga subcode as additional information for data reproduction separatelyfrom said user data to be recorded on said each sector; and subcodeadding means for recording said user data and said subcode in said eachsector.
 12. The data recording apparatus according to claim 11 ,wherein: said user data includes video data, audio data, caption data,multiplexed data including said video data and/or said audio data and/orsaid caption data, or computer data.
 13. The data recording apparatusaccording to claim 11 , wherein said subcode generating means generatesa sector number for identifying said sector as said subcode.
 14. Thedata recording apparatus according to claim 13 , wherein said subcodegenerating means generates a predetermined time code as said subcode.15. The data recording apparatus according to claim 13 , wherein saidsubcode generating means generates entry point information representinga sector including the head position of an I-picture as said subcode,when video data in accordance with the stipulation of ISO11172 (MPEG1)or ISO13818 (MPEG2) is recorded as said user data.
 16. The datarecording apparatus according to claim 13 , wherein said subcodegenerating means generates picture type information representing thetype of a picture including in data within an associated sector as saidsubcode, when video data in accordance with the stipulation of ISO11172(MPEG1) or ISO13818 (MPEG2) is recorded as said user data.
 17. A datarecording apparatus according to claim 13 , wherein said subcodegenerating means generates temporal reference information as saidsubcode, when video data in accordance with the stipulation of ISO11172(MPEG1) or ISO13818 (MPEG2) is recorded as said user data.
 18. The datarecording apparatus according to claim 13 , wherein said subcodegenerating means generates copyright information for video data, audiodata, caption data, or computer data as said subcode.
 19. The datarecording apparatus according to claim 13 , wherein said subcodegenerating means generates an application identification codecorresponding to an application associated with data in a sector, andinformation on each application as said subcode.
 20. The data recordingapparatus according to claim 13 , wherein said subcode generating meansgenerates track information as said subcode.
 21. A data recording mediumfor recording data thereon in the unit of sector, wherein: a subcode isrecorded as additional information for data reproduction in said datasector separately from said data.
 22. The data recording mediumaccording to claim 21 , wherein video data audio data, caption data,multiplexed data including said video data and/or said audio data and/orsaid caption data, or computer data is recorded as said data.
 23. Thedata recording medium according to claim 21 , wherein said subcodeincludes a sector number for identifying said sector.
 24. The datarecording medium according to claim 23 , wherein said subcode includes apredetermined time code.
 25. The data recording medium according toclaim 23 , wherein said subcode includes entry point informationrepresenting a sector including a head position of an I-picture, whenvideo data in accordance with the stipulation of ISO11172 (MPEG1) orISO13818 (MPEG2) is recorded as said user data.
 26. The data recordingmedium according to claim 23 , wherein said subcode includes picturetype information representing the type of a picture including in datawithin an associated sector, when video data in accordance with thestipulation of ISO11172 (MPEG1) or ISO13818 (MPEG2) is recorded as saiduser data.
 27. The data recording medium according to claim 23 , whereinsaid subcode includes temporal reference information, when video data inaccordance with the stipulation of ISO11172 (MPEG1) or ISO13818 (MPEG2)is recorded as said user data.
 28. The data recording medium accordingto claim 23 , wherein said subcode includes copyright information forvideo data, audio data, caption data, or computer data.
 29. The datarecording medium according to claim 23 , wherein said subcode includesan application identification code corresponding to an applicationassociated with data in a sector, and information on each application.30. The data recording medium according to claim 23 , wherein saidsubcode includes track information.
 31. A data reproducing method forreproducing a data recording medium which has a subcode serving asadditional information for data reproduction recorded in each sectorseparately from user data when the user data was recorded in the unit ofsaid sector, wherein: said subcode recorded in said each sector isreproduced; reproduction of said user data is controlled based on saidreproduced subcode.
 32. The data reproducing method according to claim31 , wherein video data, audio data, caption data, multiplexed dataincluding said video data and/or said audio data and/or caption data, orcomputer data is recorded as said data on said recording medium.
 33. Thedata reproducing method according to claim 31 , wherein: said subcodeincludes a sector number for identifying said sector, and reproductionof said user data is controlled based on said sector number.
 34. Thedata reproducing method according to claim 33 , wherein: said subcodeincludes a predetermined time code, and reproduction of said user datais controlled based on said time code.
 35. The data reproducing methodaccording to claim 33 , wherein: said subcode includes entry pointinformation representing a sector including the head position of anI-picture as said subcode, when video data in accordance with thestipulation of ISO11172 (MPEG1) or ISO13818 (MPEG2) is recorded as saiduser data, and reproduction of said user data is controlled based saidentry point information.
 36. The data reproducing method according toclaim 33 , wherein: said subcode includes picture type informationrepresenting the type of a picture included in data within an associatedsector, when video data in accordance with the stipulation of ISO11172(MPEG1) or ISO13818 (MPEG2) is recorded as said user data, andreproduction of said user data is controlled based on said picture typeinformation.
 37. The data reproducing method according to claim 33 ,wherein: said subcode includes temporal reference information, whenvideo data in accordance with the stipulation of ISO11172 (MPEG1) orISO13818 (MPEG2) is recorded as said user data, and reproduction of saiduser data is controlled based on said temporal reference information.38. The data reproducing method according to claim 33 , wherein: saidsubcode includes copyright information for video data, audio data,caption data, or computer data, and a limit to duplication is controlledbased on said copyright information.
 39. The data reproducing methodaccording to claim 33 , wherein: said subcode includes an applicationidentification code corresponding to an application associated with datain a sector and information on each application, and reproduction ofsaid user data is controlled based on said application identificationcode and said information on each application.
 40. The data reproducingmethod according to claim 33 , wherein: said subcode includes trackinformation, and reproduction of said user data is controlled based onsaid track information.
 41. The data reproducing method according toclaim 31 , wherein: said subcode i s extracted fro reproduced databefore said data is demultiplexed, when a predetermined one of saidsectors is randomly accessed.
 42. The data reproducing method accordingto claim 31 , wherein: part of an error correction code is only used toperform error correction for said subcode, when a predetermined one ofsaid sectors is randomly accessed.
 43. A data reproducing apparatus forreproducing a data recording medium which has a subcode serving asadditional information for data reproducing recorded in each sectorseparately from user data when the user data was recorded in the unit ofsaid sector, comprising: reproducing means for reproducing user datarecorded in said each sector; subcode reproducing means for reproducingsaid subcode recorded in said each sector; and control means forcontrolling reproduction of said user data based on said reproducedsubcode.
 44. The data reproducing apparatus according to claim 43 ,wherein video data, audio data, caption data, multiplexed data includingsaid video data and/or audio data and/or said caption data, or computerdata is recorded on said data recording medium as said user data. 45.The data reproducing apparatus according to claim 43 , wherein: saidsubcode includes a sector number for identifying said sector, and saidcontrol means controls reproduction of said user data based on saidsector number.
 46. The data reproducing apparatus according to claim 43, wherein: said subcode includes predetermined time code, and saidcontrol means controls reproduction of said user data based on said timecode.
 47. The data reproducing apparatus according to claim 45 ,wherein: said subcode includes entry point information representing asector including the head position of an I-picture as said subcode, whenvideo data in accordance with the stipulation of ISO11172 (MPEG1) orISO13818 (MPEG2) is recorded as said user data based on said entry pointinformation.
 48. The data reproducing apparatus according to claim 45 ,wherein: said subcode includes picture type information representing thetype of a picture included in data within an associated sector, whenvideo data in accordance with the stipulation of ISO11172 (MPEG1) orISO13818 (MPEG2) is recorded as said user data, and said control meanscontrols reproduction of said user data based on said picture typeinformation.
 49. The data reproducing apparatus according to claim 45 ,wherein: said subcode includes temporal reference information, whenvideo data in accordance with the stipulation of ISO11172 (MPEG1) orISO13818 (MPEG2) is recorded as said user data, and said control meanscontrols reproduction of said user data based on said temporal referenceinformation.
 50. The data reproducing apparatus according to claim 45 ,wherein: said subcode includes copyright information for video data,audio data, caption data, or computer data, and said control meanscontrols a limit to duplication of said respective data based on saidcopyright information.
 51. The data reproducing apparatus according toclaim 45 , wherein: said subcode includes an application identificationcode corresponding to an application associated with data in a sectorand information on each application, and said control means controlsreproduction of said user data based on said application identificationcode and said information on each application.
 52. The data reproducingapparatus according to claim 45 , wherein: said subcode includes trackinformation, and said control means controls reproduction of said userdata based on said track information.
 53. The data reproducing apparatusaccording to claim 43 , wherein: said subcode reproducing means extractssaid subcode from reproduced data before said reproduced data isdemultiplexed, when a predetermined one of said sectors is randomlyaccessed.
 54. The data reproducing apparatus according to claim 43 ,wherein: part of an error correction code is only used to perform errorcorrection for said subcode, when a predetermined one of said sectors israndomly accessed.